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2020 6.6 D-max towing MPG

Lfod1836

By Lfod1836
in 6.6L Duramax Diesel (L5P)

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Lfod1836
Lfod1836

That's actually really encouraging! Considering I can't even get 10 MPG with my 16' LTZ 5.3 pulling my 6500 lb Jayco at 55 mph. It has the 8 speed and will never even think about going into 7th g

Lfod1836
Lfod1836

I understand MPG is not why anyone gets a bigger truck with a diesel. You can buy a lot of fuel with that $9k additional diesel premium. My #1 reason for the bigger truck is safety in pulling my

cNate
cNate

2020 GMC Sierra AT4 2500 Duramax towing 9k bumper pull travel trailer. I’m seeing about 10 MPG all around, when I haul from sea level to Eastern Sierra Nevadas (8k foot climb) and back. Averaging 65-7

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Lfod1836 Enthusiast

Lfod1836

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On 2/20/2020 at 2:21 PM, rblanch said:

Hauled a 40' toy hauler around 17,000# around 1,200 miles over the last week and averaged 8.5 mpg about the same as my 2017 L5P with 6 speed.

Not bad!! What was your average speed?

  • 2 weeks later...
cNate Enthusiast

cNate

Posted
Posted

2020 GMC Sierra AT4 2500 Duramax towing 9k bumper pull travel trailer. I’m seeing about 10 MPG all around, when I haul from sea level to Eastern Sierra Nevadas (8k foot climb) and back. Averaging 65-70 MPH. If I drop down to 55-60 MPH, as the speed limit in CA is 55 MPH when towing, then I see a couple MPG pickup. Towing up and down the coast at mostly sea level, I see more like 14 MPG.

I also didn’t get the truck for MPG, the big difference over my gas truck is a rip right up 6%+ grades at 60 MPH at 2k RPMs with the trans barely heating up. My old truck struggled up grades when towing (35-45 MPH) and I go to the mountains often with the trailer. 8-10x per year. More importantly than going up, I can safely come down with my wife and kids. The old truck concerned me about breaks over heating. Not anymore with the “exhaust break”. That back pressure from the turbo brings this whole setup to a crawl on step inclines. Love the truck. The tech, the power, and control!




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Lfod1836 Enthusiast

Lfod1836

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5 hours ago, cNate said:

I also didn’t get the truck for MPG, the big difference over my gas truck is a rip right up 6%+ grades at 60 MPH at 2k RPMs with the trans barely heating up. My old truck struggled up grades when towing (35-45 MPH) and I go to the mountains often with the trailer. 8-10x per year. More importantly than going up, I can safely come down with my wife and kids. The old truck concerned me about breaks over heating. Not anymore with the “exhaust break”. That back pressure from the turbo brings this whole setup to a crawl on step inclines. Love the truck. The tech, the power, and control!

 

This is EXACTLY why I am upgrading to HD Diesel when only pulling a 8k# TT. 

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  • 7 months later...
Lfod1836 Enthusiast

Lfod1836

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Posted (edited)

Finally purchased my 20' 2500 D-Max High country. First pull 400 miles. 7k TT 11 MPG. Flat land from Houston to Oklahoma. Before I left I noticed my soot level was at 80%. I did not want it to start a regen while towing so I used my banks idash to initiate a moving regen. Love this banks idash!! Funny thing was that once I was towing the EGT stays around 750 deg. And that is high enough to keep the soot level from climbing. At times it would even go down a bit.

 

Another strange thing is the transmission temp. I am used to a transmission somewhat leveling out when traveling across flat land. However I noticed the temp would climb to around 160 then drop back down to around 145. The surround camera are absolutely amazing!!

2020-10-15 14.00.09.jpg

Edited by Lfod1836
  • 5 weeks later...
  • 2 weeks later...
Blasts Enthusiast

Blasts

Posted
Posted

I know 2500 has 11.5" and 3500 has 12" ring pinion gears but they have same gear ratio 3.42.   So  Are they same mpg?

shadow gray 2020 hd Enthusiast

shadow gray 2020 hd

Posted
Posted

Only pulled my old bumper pull stock trailer a few times, but averaged about 13 according to the display.  That was short distance in tow/haul mode and with some idling to load and drop off.  Have yet to haul the equipment trailer with it.

  • 3 weeks later...
BigKahuna Enthusiast

BigKahuna

Posted
Posted
On 12/10/2020 at 1:50 PM, Laidback said:

What mpg are you guys getting without towing a trailer?

Around 17-18 mostly highway with some city mixed in.

rblanch Enthusiast

rblanch

Posted
Posted

I get 8 mpg towing 17,000 # 5th wheel toy hauler . My 2017 got 10 pulling the same trailer. the 10 speed with 3.42 axle ratio comes out of over drive a lot more at 68mph than the 2017 with 6 speed and 3.73 gearing.

  • 3 weeks later...
rauan Enthusiast

rauan

Posted
Posted

I am getting around 11 MPG with my RAM 1500 EcoDiesel towing my 7.5k travel trailer. Should I expect the same MPG with AT4 6.6 Duramax or less? 

  • 4 months later...
aliveguy5 Enthusiast

aliveguy5

Posted
Posted

I get 9-11mpg towing a 7,500 TT with a half-ton 6.2 TB towing at 75mph. I just put a deposit down on 2500 Dmax as I feel it's much safer to have a bigger truck at this weight and speed regardless how good the 1/2 ton felt pulling the trailer. 

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